I'm looking for a module so that i can switch litestep themes with a !bang command. I've seen one, called switch.dll, but this pops up an error and fails to run when i load litestep. Does anyone know of any other modules or methods that i could use to achieve this? Thanks.

You can use LSTS like this:
"...\LSTS.exe" "$ThemeDir$$ThemeName$.thm"

you can always do "litestep.exe themes\blah\step.rc" if the themes aren't OTS compliant.